Flexible electronics have a wide variety of potential applications that include communications, medical sensing, diagnostics, entertainment, analytics, and many other uses. Devices, sensors, indicators, and other circuitry can be disposed on a flexible substrate that is configured to conform to irregular or dynamic three-dimensional surfaces. Such devices can be adapted for use in wearable devices, skin-adhering devices, or devices not optimal for mounting a rigid circuit such as tires, flexible displays, fabrics, or other surfaces subject to deformation, vibration, or other forces.
Flexible devices have been produced that generally include a flexible substrate patch. Adhesive material can be included on one side of the patch for mounting on a surface such as fabric or skin, and electrical components can be included in or on the substrate patch. In another example, a patch can be attached with a tape, or held in place via a restraining body. While such devices can be configured to bend in and out of a plane of the substrate patch in response to motion of surface, such bending does not optimally account for the complex forces and motions resulting from three-dimensional surface motion and deformation.
For example, such patches generally have a limited range of motion, and are generally not adapted to compensate for deformation, and thus have a relatively limited stretchability. Delamination between the device and the surface can occur in regions where the device is unable to comport with the three-dimensional motion. This can lead to detachment of the device from the surface, interruption impedance, or damage of operation of the device, and other undesirable outcomes. An example of this phenomenon is easily illustrated with a customary adhesive bandage. Not only does the bandage lose adherence over time due to relative motion between a user's skin and the adhesive surface of the bandage, but also, the limited stretchability of the bandage can cause the user discomfort. The user may feel their skin being pulled by the bandage when they move a nearby joint that results in the deformation of nearby skin.
Techniques have been proposed for decreasing delamination between a flexible device and a surface. In one example, U.S. Pat. No. 8,520,399, issued Aug. 27, 2013, describes cuts or perforations in the substrate that are arranged to increase a stretchability of the substrate. Where a definition or use of a term in a reference is inconsistent or contrary to the definition of that term provided herein, the definition of that term provided herein applies herein and the definition of that term in the reference does not apply. In another example, U.S. Pat. No. 8,389,862 describes devices with islands of rigid integrated circuits with edges separated and connected by deformable interconnects, and which are disposed on a continuous sheet of an elastomeric substrate. These approaches have a limited applicability, and can add complexity and expense to both the production of flexible devices, and to the flexible devices themselves.
What is needed, therefore, is a flexible device that is optimized for connection to irregular and dynamic surfaces. A flexible device that is also configured to deform to compensate for complex three-dimensional motion, while maintaining a relatively simple design and fabrication process, would also be beneficial.